DC-DC converters are well known. A DC-DC converter is a circuit for changing unregulated direct current (DC) input voltages into controlled or regulated DC output voltages. DC-DC converters are commonly used in power supplies, where they provide power for voltage sensitive devices.
A typical contemporary DC-DC converter, such as that shown in FIG. 1 and discussed in detail below, comprises a pulse width modulator (PWM) switch that cooperates with a power filter, a reference voltage source, a compensation amplifier and voltage/current feedback circuits to convert an unregulated DC input voltage into a regulated DC output voltage. DC-DC converters are utilized both to step down and step up unregulated DC input voltages.
Various DC-DC converter circuit topologies are known. These topologies are derived from either the basic step-down or step-up DC-DC converters. A step-down DC-DC converter, also known as a buck converter, is utilized to provide a lower DC output voltage than the input voltage. A step-up converter, also known as a boost converter, is utilized to provide a higher DC output voltage than the input voltage. A flyback converter, also known as buck-boost converter, is obtained by cascading a buck converter with a boost converter. Similarly, a boost-buck converter is obtained by cascading a boost converter with a buck converter. Other DC-DC converter topologies, such as those of resonant-link converters, are also known.
Contemporary DC-DC converters require the use of a magnetic element (i.e., a transformer or inductor) having an air gapped core. The air gapped core may be either local or distributed. It provides magnetic energy storage during the on time of the duty cycle controlled pulse width modulator switch. The air gapped core typically requires some minimum volume in order to provide the appropriate functionality for DC-DC converter operation.
As power converters and their associated circuits become more complex, it is desirable to be able to reduce the volume and form factor characteristics of their magnetic elements. Reduction in the size of such magnetic core components is typically achieved by using low profile substrates. It is also desirable to maintain a fast response for control of the DC-DC converter output as a function of load current transient demands.
Thus, it is desirable to provide a low profile DC-DC converter that is suitable for use in a variety of different circuit topologies and that is capable of rapidly compensating for load current variations while providing higher power densities.